/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.visitor;

import proguard.classfile.*;

/**
 * This <code>MemberVisitor</code> delegates its visits to another given <code>MemberVisitor</code>, but only when the
 * visited member has the proper access flags.
 * <p>
 * If conflicting access flags (public/private/protected) are specified, having one of them set will be considered
 * sufficient.
 *
 * @see ClassConstants
 *
 * @author Eric Lafortune
 */
public class MemberAccessFilter implements MemberVisitor {
    // A mask of conflicting access flags. These are interpreted in a special
    // way if more of them are required at the same time. In that case, one
    // of them being set is sufficient.
    private static final int ACCESS_MASK =
        ClassConstants.ACC_PUBLIC | ClassConstants.ACC_PRIVATE | ClassConstants.ACC_PROTECTED;

    private final int requiredSetAccessFlags;
    private final int requiredUnsetAccessFlags;
    private final int requiredOneSetAccessFlags;
    private final MemberVisitor memberVisitor;

    /**
     * Creates a new MemberAccessFilter.
     * 
     * @param requiredSetAccessFlags the member access flags that should be set.
     * @param requiredUnsetAccessFlags the member access flags that should be unset.
     * @param memberVisitor the <code>MemberVisitor</code> to which visits will be delegated.
     */
    public MemberAccessFilter(int requiredSetAccessFlags, int requiredUnsetAccessFlags, MemberVisitor memberVisitor) {
        this.requiredSetAccessFlags = requiredSetAccessFlags & ~ACCESS_MASK;
        this.requiredUnsetAccessFlags = requiredUnsetAccessFlags;
        this.requiredOneSetAccessFlags = requiredSetAccessFlags & ACCESS_MASK;
        this.memberVisitor = memberVisitor;
    }

    // Implementations for MemberVisitor.

    public void visitProgramField(ProgramClass programClass, ProgramField programField) {
        if (accepted(programField.getAccessFlags())) {
            memberVisitor.visitProgramField(programClass, programField);
        }
    }

    public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod) {
        if (accepted(programMethod.getAccessFlags())) {
            memberVisitor.visitProgramMethod(programClass, programMethod);
        }
    }

    public void visitLibraryField(LibraryClass libraryClass, LibraryField libraryField) {
        if (accepted(libraryField.getAccessFlags())) {
            memberVisitor.visitLibraryField(libraryClass, libraryField);
        }
    }

    public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod) {
        if (accepted(libraryMethod.getAccessFlags())) {
            memberVisitor.visitLibraryMethod(libraryClass, libraryMethod);
        }
    }

    // Small utility methods.

    private boolean accepted(int accessFlags) {
        return (requiredSetAccessFlags & ~accessFlags) == 0 && (requiredUnsetAccessFlags & accessFlags) == 0
            && (requiredOneSetAccessFlags == 0 || (requiredOneSetAccessFlags & accessFlags) != 0);
    }
}
